A PlotDigitizer alternative that reads the points itself
PlotDigitizer's free online app has you calibrate the axes and place points by hand; automatic tracing is part of its paid Pro licence. Chart to Data reads axes and points automatically from the start.
What you get
- Automatic reading of bars, lines, markers and error bars.
- Charts inside PDFs read from the drawing, not from pixels. When a PDF holds the chart as a drawing (most figures in papers do), the values are read from the drawing itself. Nothing is estimated from pixels, so a point is as precise as the file is.
- Excel with one sheet per chart and an audit sheet, or CSV, or copy and paste.
What to expect from pictures
A picture (a screenshot, a scan, a PNG or JPEG) is read by an AI model. Every value is then drawn back on the picture as a ring, so a wrong one is easy to see and to correct in the table.
Small, crowded figures are the hard case for pictures: when a plot is only a couple of hundred pixels high, a pixel is already a visible error. Use the PDF when you have it, or a larger screenshot.
Questions
Does it work offline?
No. It runs in the browser and reads the file on our server. The file is discarded after reading.
Which chart types does it read?
Bar charts (grouped, stacked, horizontal), line charts, scatter plots, pie and ring charts, and survival curves with their number-at-risk table. Log axes, date axes, two y axes and error bars are read.